code: def test_timegapsplit_without_train_duration():
      cv = TimeGapSplit(
          date_serie=df["date"],
          train_duration=None,
          valid_duration=timedelta(days=3),
          gap_duration=timedelta(days=5),
          n_splits=3,
      )
      csv = list(cv.split(X_train, y_train))
  
      assert len(csv) == 3
      assert cv.train_duration == timedelta(days=10)
  
file_path: scikit-lego/tests/test_model_selection/test_timegapsplit.py
imports: import datetime
  from datetime import timedelta
  import numpy
  import pandas
  import pytest
  from sklearn.linear_model import Lasso
  from sklearn.model_selection import GridSearchCV
  from sklearn.pipeline import Pipeline
  from sklego.model_selection import TimeGapSplit
label_desc: Use image node_id 6 for calling a global function with example usage: test_timegapsplit_without_train_duration() without return types